Microbead and nanophase carbon materials attract many researchers due to their unique applications, [1] which include high-density and high-strength carbon artifacts, [2] super-active carbon beads of high surface area, [3] lithium storage, [4a] lithium battery anodes, [4b-d] spherical packing materials for HPLC, [5] hydrogen storage applications, [6] and catalysis. [7] Much attention has focused on the preparation (precursors and methods) and properties of these carbon materials, because their applications significantly depend on the shape and size of the particles.Carbon nitrides are of current interest due to their novel mechanical, optical, and tribological properties, including low density, extreme hardness, surface roughness, wear resistance, chemical inertness, and biocompatibility.[8] These superhard diamondlike materials promise a variety of technological and biological applications. For example, they are used as biocompatible coatings on biomedical implants, [8][9] battery electrodes, [10] catalytic supports, [11] gas separation systems, [12] electronic materials, [13] and humidity and gas sensors.[14]Unlike carbon-based materials, applications of carbon nitrides are not only governed by the texture and size of the particles [13] but also by the relative nitrogen content. As a consequence, an extensive effort has focused on the discovery of precursors along with the appropriate methods to increase the nitrogen content in carbon nitrides.There is very little literature on the preparation of carbon nanospheres and nitrogen-rich carbon nitrides (> 60 wt % N). Gillan reported preparations of carbon nitrides C 3 N 4 (60.9 wt % N) and C 3 N 5 (66.0 wt % N) and graphitic carbon using high-nitrogen 2,4,6-tri(azido)-1,3,5-triazine as the pre-

Microbead and nanophase carbon materials attract many researchers due to their unique applications, [1] which include high-density and high-strength carbon artifacts, [2] super-active carbon beads of high surface area, [3] lithium storage, [4a] lithium battery anodes, [4b-d] spherical packing materials for HPLC, [5] hydrogen storage applications, [6] and catalysis. [7] Much attention has focused on the preparation (precursors and methods) and properties of these carbon materials, because their applications significantly depend on the shape and size of the particles.Carbon nitrides are of current interest due to their novel mechanical, optical, and tribological properties, including low density, extreme hardness, surface roughness, wear resistance, chemical inertness, and biocompatibility.[8] These superhard diamondlike materials promise a variety of technological and biological applications. For example, they are used as biocompatible coatings on biomedical implants, [8][9] battery electrodes, [10] catalytic supports, [11] gas separation systems, [12] electronic materials, [13] and humidity and gas sensors.[14]Unlike carbon-based materials, applications of carbon nitrides are not only governed by the texture and size of the particles [13] but also by the relative nitrogen content. As a consequence, an extensive effort has focused on the discovery of precursors along with the appropriate methods to increase the nitrogen content in carbon nitrides.There is very little literature on the preparation of carbon nanospheres and nitrogen-rich carbon nitrides (> 60 wt % N). Gillan reported preparations of carbon nitrides C 3 N 4 (60.9 wt % N) and C 3 N 5 (66.0 wt % N) and graphitic carbon using high-nitrogen 2,4,6-tri(azido)-1,3,5-triazine as the pre-

Carbon nitrides are of current interest due to their novel mechanical, optical, and tribological properties including low density, surface roughness, wear resistance, chemical inertness, and biocompatibility. [1][2][3][4] These superhard diamondlike materials promise a variety of technological and biological applications, for example, biocompatible coatings on biomedical implants, [5][6] battery electrodes, [7][8] gas-separation systems, [9] corrosion protection, [10] and humidity and gas sensors.[11] As these applications are primarily governed by the particle size, material texture, and nitrogen content, an extensive effort has focused on the discovery of precursors along with appropriate methods to control the size, regulate the texture, and increase the nitrogen content of carbon nitrides. We report here three novel nitrogen-rich nanolayered, nanoclustered, and nanodendritic carbon nitrides that were prepared from 4,4',6,6'-tetra(azido)azo-1,3,5-triazine (TAAT), a member of a unique class of high-nitrogen C,N-containing energetic materials.Gillan reported the preparation of single-textural carbon nitrides C 3 N 4 (60.9 wt % N, 1 = 1.82 g cm À3 ) and C 3 N 5 (66.0 wt % N, 1 = 1.82 g cm À3 ) by pyrolyses of 2,4,6-tri-(azido)-1,3,5-triazine (TAT) at 85 8C.[12] Although pressurization was not required for making C 3 N 4 , 6 atm of N 2 was needed in the preparation of C 3 N 5 . Other preparative methods using 1,3,5-triazine- [4,13,14] and 2,5,8-heptazinebased [3,[15][16][17] compounds as precursors have involved either applied pressure, high temperature, shock compression, or combinations of at least two of these conditions; however, the products obtained were nitrogen-poor materials, occasionally contaminated with hydrogen-incorporating byproducts. Our preparative protocols using TAAT yield three novel morphologies of nitrogen-rich carbon nitrides C 2 N 3 (63.6 wt % N, 1 = 1.32 AE 0.01 g cm À3 ) and C 3 N 5 (66.0 wt % N, 1 = 0.44 AE 0.01 and 1.08 AE 0.01 g cm À3 ). The pyrolyses are simple, occur under mild conditions (i.e., low temperature and without applied pressure), and require no vacuum systems, extraction, carbonization, or purification. TAAT was proposed as one of the intermediates in the decomposition of TAT, [12] and we recently developed a three-step synthetic pathway for this material. [18] Nitrogen-rich C 2 N 3 was prepared under a nitrogen atmosphere.[19] A 1.0 g crystalline sample of TAAT was loaded into a 50-mL stainless steel bomb, which was heated to 160 8C over 3 h and held at this temperature for an additional 4 h. The temperature was then increased to 185 8C over 5 h and maintained at this temperature overnight to yield glassy nanolayered C 2 N 3 carbon nitride with a density of 1.32 AE 0.01 g cm À3 . The glassy nanolayer was characterized by IR spectroscopy, gas pycnometry (GP), elemental analysis, thermogravimetric analysis (TGA), [20] and SEM imaging (Figure 1).The interlinked three-dimensional network of glassy pockets shown in Figure 1 (right) suggested that the conversion to C 2 N 3 inv...

Carbon nitrides are of current interest due to their novel mechanical, optical, and tribological properties including low density, surface roughness, wear resistance, chemical inertness, and biocompatibility. [1][2][3][4] These superhard diamondlike materials promise a variety of technological and biological applications, for example, biocompatible coatings on biomedical implants, [5][6] battery electrodes, [7][8] gas-separation systems, [9] corrosion protection, [10] and humidity and gas sensors.[11] As these applications are primarily governed by the particle size, material texture, and nitrogen content, an extensive effort has focused on the discovery of precursors along with appropriate methods to control the size, regulate the texture, and increase the nitrogen content of carbon nitrides. We report here three novel nitrogen-rich nanolayered, nanoclustered, and nanodendritic carbon nitrides that were prepared from 4,4',6,6'-tetra(azido)azo-1,3,5-triazine (TAAT), a member of a unique class of high-nitrogen C,N-containing energetic materials.Gillan reported the preparation of single-textural carbon nitrides C 3 N 4 (60.9 wt % N, 1 = 1.82 g cm À3 ) and C 3 N 5 (66.0 wt % N, 1 = 1.82 g cm À3 ) by pyrolyses of 2,4,6-tri-(azido)-1,3,5-triazine (TAT) at 85 8C.[12] Although pressurization was not required for making C 3 N 4 , 6 atm of N 2 was needed in the preparation of C 3 N 5 . Other preparative methods using 1,3,5-triazine- [4,13,14] and 2,5,8-heptazinebased [3,[15][16][17] compounds as precursors have involved either applied pressure, high temperature, shock compression, or combinations of at least two of these conditions; however, the products obtained were nitrogen-poor materials, occasionally contaminated with hydrogen-incorporating byproducts. Our preparative protocols using TAAT yield three novel morphologies of nitrogen-rich carbon nitrides C 2 N 3 (63.6 wt % N, 1 = 1.32 AE 0.01 g cm À3 ) and C 3 N 5 (66.0 wt % N, 1 = 0.44 AE 0.01 and 1.08 AE 0.01 g cm À3 ). The pyrolyses are simple, occur under mild conditions (i.e., low temperature and without applied pressure), and require no vacuum systems, extraction, carbonization, or purification. TAAT was proposed as one of the intermediates in the decomposition of TAT, [12] and we recently developed a three-step synthetic pathway for this material. [18] Nitrogen-rich C 2 N 3 was prepared under a nitrogen atmosphere.[19] A 1.0 g crystalline sample of TAAT was loaded into a 50-mL stainless steel bomb, which was heated to 160 8C over 3 h and held at this temperature for an additional 4 h. The temperature was then increased to 185 8C over 5 h and maintained at this temperature overnight to yield glassy nanolayered C 2 N 3 carbon nitride with a density of 1.32 AE 0.01 g cm À3 . The glassy nanolayer was characterized by IR spectroscopy, gas pycnometry (GP), elemental analysis, thermogravimetric analysis (TGA), [20] and SEM imaging (Figure 1).The interlinked three-dimensional network of glassy pockets shown in Figure 1 (right) suggested that the conversion to C 2 N 3 inv...